Atomic structure and the periodic table flashcards

Students must understand that atoms are made of protons, neutrons and electrons, and know the relative masses and charges of each particle. The atomic number tells you the number of protons, while the mass number gives the total of protons and neutrons. Electrons are arranged in shells around the nucleus, and this arrangement determines how an element behaves chemically. The periodic table organises elements in order of atomic number, with elements in the same group sharing similar properties because they have the same number of outer electrons. Students should also understand isotopes, the development of atomic models over time, and how the modern periodic table differs from Newlands and Mendeleev's early attempts at classification.

1. Card 1

   What three particles make up an atom?

   Atoms contain protons and neutrons in the nucleus, with electrons arranged in shells around the outside.

2. Card 2

   What is the atomic number of an element?

   The atomic number is the number of protons in the nucleus. It identifies the element and determines its position in the periodic table.

3. Card 3

   How do you calculate the number of neutrons in an atom?

   Subtract the atomic number from the mass number. For example, sodium has mass number 23 and atomic number 11, so it has 12 neutrons.

4. Card 4

   What are isotopes?

   Isotopes are atoms of the same element with the same number of protons but different numbers of neutrons, giving them different mass numbers.

5. Card 5

   What are the relative charges of a proton, neutron and electron?

   A proton has a charge of +1, a neutron has no charge (0), and an electron has a charge of -1.

6. Card 6

   How are electrons arranged in the first three shells of an atom?

   The first shell holds up to 2 electrons, the second holds up to 8, and the third also holds up to 8 electrons.

7. Card 7

   Why do elements in the same group of the periodic table have similar properties?

   They have the same number of outer electrons, which controls how they react chemically.

8. Card 8

   What did Mendeleev contribute to the development of the periodic table?

   Mendeleev arranged elements by atomic mass, left gaps for undiscovered elements, and predicted their properties, making his table widely accepted.

9. Card 9

   What is the difference between a group and a period in the periodic table?

   A group is a vertical column of elements with the same outer electron count. A period is a horizontal row where a new electron shell is being filled.

10. Card 10

    What is the charge and relative mass of an electron?

    An electron has a charge of -1 and a relative mass of approximately 1/1836, so it contributes almost nothing to the overall mass of an atom.

11. Card 11

    How did the nuclear model of the atom replace the plum pudding model?

    Rutherford's alpha particle scattering experiment showed most mass is in a tiny, positive nucleus, disproving Thomson's spread-out positive charge model.

12. Card 12

    Why are atoms electrically neutral?

    Atoms have equal numbers of protons and electrons, so the positive and negative charges cancel out, giving an overall charge of zero.

• Students often confuse atomic number with mass number, forgetting that atomic number counts only protons, not neutrons.
• A common error is thinking isotopes of an element have different chemical properties, when in fact their chemistry is almost identical.
• Many students forget that in a neutral atom the number of electrons always equals the number of protons, not the mass number.

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